US2732443A - Friction latched electroresponsive switch - Google Patents

Description

Jan. 24, 1956 w. ROTH 2,732,443

FRICTION LATCHED ELECTRORESPONSIVE SWITCH Filed Feb. 28, 1952 Invenbor Adrian W Roth by W Hi8 Atl ivorne 1.

United States Patent 2,732,443 FRICTION LATCHED ELECTRORESPONSIVE SWETCH Adrian W. Roth, Media, la., assignor to General Electric (lompany, a corporation of New York Application February 28, 1952, Serial No. 273,999 16 Claims. (Cl. 2tl05) The invention relates to electroresponsive switches and the principal object is to provide an improved friction latched type of electroresponsive switch which is particularly suitable for short circuiting the contacts of mechanical rectifiers immediately in response to the occurrence of are back, but is applicable to many other electrorespon sive high current switching services where substantially instantaneous response and circuit controlling operation of the switch in less than M of a second is desirable.

A mechanical detent switch latching mechanism, such as commonly employed for holding a switch member against an operating or biasing force, inherently is too slow for such high speed electroresponsive tripping operation. This is particularly true where a relatively strong biasing force is necessary to enable the switch to quickly and positively control relatively large currents for example of the order of fifty or sixty thousand amperes. In such a case the latching detent must be correspondingly strong and of heavy construction. Hence too much time delay and too much tripping force are inherently involved in moving such a detent the substantial distance required to release a strongly biased heavy duty switch. In case a series of interconnected detents are provided in order to reduce the tripping force requirement or to obtain a greater sensitivity of the electroresponsive tripping device, then the total time required for sequentially tripping the series of detents may become even longer.

Such inherent tripping time delay can be reduced to a minimum by means of the improved friction clamping type of switch latching mechanism of the present invention where an infinitesimal relative lateral movement of relatively light weight friction clamping elements is sufficient to release a relatively large biasing force for substantially instantaneously operating a switch of relatively large current carrying capacity. Furthermore, when an electroresponsive device of a type having a very high speed of response is combined to release the friction clamping device of the strongly biased movable switch member then response and operation of a large current capacity switch can be obtained substantially instantaneously upon the occurrence of a predetermined electrical condition.

Thus it is an object of my invention to provide a friction latched switch mechanism having relatively light but strong tension elements mounted to extend on opposite sides of each switch member and transmit a lateral compressive force for frictionally clamping the member therebetween against a strong switch operating or biasing force so as to require upon release of the lateral compressive clamping force a practically infinitesimal amount of lateral unclamping motion of the friction clampingtension elements to release the switch member for substantially instantaneous circuit controlling movement in accordance with its bias.

Another object is to repeatedly utilize the friction element lateral clamping force by interleaving a row of laterally movable friction clamping tension elements with a row of laterally movable biased switch members so that each switch member when frictionally clamped between its adjacent tension elements transmits the clamping force for frictionally clamping the next switch member intherow between its adjacent friction clamping tension ele ments. In this way, the quick release of the clamping force on any switch member will simultaneously release the clamping force on all switch members in the row.

Another object is to provide a high speed electrore ?atented Jan 24-, 1135 sponsive device with connections for releasing or rendering ineffective a strong biasing spring that supplies the lateral clamping force to the interleaved rows of friction clamping tension elements and biased switch members so as to enable each frictionally held switch member to be released immediately upon the occurrence of a predetermined electrical condition.

Another object is to provide mechanism for resetting the row of switch members against their bias into clamping position between the interleaved row of friction clamping tension elements and resetting the electroresponsive clamping spring releasing device.

Other objects and advantages will appear in the following description of the accompanying drawing in which Fig. 1 is a top view of an electroresponsive releasable friction latched multiple contact switch mechanism embodying the improvements of the present invention in a form suitable for carrying very large currents such as produced upon short circuiting the contacts of a polyphase power current mechanical rectifier. Fig. 2 is a sectional view on the line 2-2 of Fig. 1 more clearly illustrating the details of construction of the short circuiting switch members and their associated friction clamping parts. Fig. 3 is a partial sectional view on the line 33 of Fig. 2 showing further details of construction of the high speed releasing electromagnets and the reset mechanism. Fig. 4 is an enlarged view of the movable short circuiting switch members shown in Fig. 2 with the switch members in the open position in which they are clamped between the adjacent friction elements and thereby held against operation by a strong leaf biasing spring. Fig. 5 is a sectional view on the line 55 of Fig. 4 showing the manner of interleaving the row of movable switch members and the row of friction clamping and tension restraining elements therefor. Fig. 6 is a partial sectional view of a modification utilizing a high speed piezoelectric element for releasing the friction clamping tension elements in response to a predetermined electrical condition such as when a high voltage excitation is removed from the piezoelectric element.

Referring now to Figs. 1 and 5, a plurality of movable switch members 10 are shown loosely positioned in a row with one end interleaved between a row of friction clamping tension elements 11 to be frictionally clamped therebetween against the strong closing bias of the separate leaf biasing springs 12 that engage with the central nibs 10 of the switch members as more clearly shown in Fig. 4. Each movable switch member 10 has a rocking and free lateral sliding hearing at the other end on a terminal member 13 and is strongly biased by the leaf spring 12 to the closed position to electrically connect the heavy current conducting terminal element 13 with the oppositely spaced apart heavy current terminal element 14. Thus when released the plurality of relatively light weight switch members 10 can short circuit very large currents of the order of fitfy or sixty thousand amperes between the terminals 13 and 14. The

- plurality of switch members 10 in parallel produce at such high currents a very low voltage drop. Moreover the strong biasing springs 12 in cooperation with the magnetic forces from the loop formed by the terminals.

13, 14 and 14a maintain effective contact even at such high currents.

The terminal 13 is mounted by means of screw 15 on the U-shaped frame member 16 that is secured between the side plates 17 and 18. These side plates are clamped together by means of the clamping bolts 19 and that extend through the insulating spacer blocks 20 and 20a and are secured by the opposing clamping nuts 21 and As shown in Figs. 2 and 3, the friction clamping elements 11 preferably operate under tension in resisting the switch biasing force of spring 12 and hence may be in the form of thin steel plates clamped at one end 3 in a row on the supporting bolts 25. Suitable spacer elements 26 are interposed between the friction clamping elements 13.1 and specially recessed so as to provide for relatively free lateral movement of the other "ends of the clamping elements 3.31 in frictional engagement with opposite sides of the interleaved switch members The spacer elements 26 are mounted between the arsanae come the bias of all the strong leaf biasing springs 12.

The cam shaft 57 is also provided with the earns 62 for I engaging the insulated end $3 of the bell crank levers64 n'ct'ically held by the movably mounted electromagnet 34 serves to ap'ply the lateral clamping force. As shown in Figs. 1 and 3, the frame 35 of electromagnet 3-: is mouhted on a movable platform or plate 36 by rhean's of the angle irons 37 and mounting bolts 38. Plate or platform 36 is slidably mounted at its opposite ends 'on the bolts 19 and 19a with the com ression springs 49 and 40a interposed between plate 36 and the adjustable compression nuts 41 and 41a to strongly bias the: plate 36 so that upon release of the magnet a'rmatu're's 33 and 33a plate 36 comes into engagement with suitable resilient shock absorbing stops 42 the are mounted by riieans of nuts 43 'at the outer ends of the "bolts 19 and i911. Thus, the strong forces of the compression spr'i'ng's -40 and-49a are transmitted through the slida'ble "plate '36 to electromagnet 34 and through the armature 33 when magnetically held by the electromagnet 34 to the lever 28 and thereby applied to clamp the interleaved rows of contacts It and friction elements '11 together so as frictio'nally hold the contacts it against movement by their strong biasing springs 12. In this way, the row of switch members it) are held frictionally' latched in the open position outof engagement with the terminal 14 as shown in Fig. '4.

A duplicate row of switch member 10a together with an interleaved row of friction clamping elements 11c and biasing springs 12a are mounted on the opposite side of the central terminal 13 and arranged in exactly the same way to be frictionally clamped together out of engagement with terminal 14a by means of the ar' mature 33a and movably mounted electromagnet 3411. Thus, the row of "contacts 10a serve to interconnect the central terminal 13 with the terminal 14:: when the armature 33a "is released from attractive engagement with the .poles of the 'elec'tromagnet 34h.

As shown in Figs 2 and '3, a pair of U-shaped supporting members 46 are mounted upon but insulated from the base mounting channels 47 by means of the insulating blocks 4-8. The friction latched switch mechanism '49 and the movably mounted electromagnet assembly 54) are mounted in cooperating relation on the U-shaped su porting members 46 "by means or the through bolts 19 and 19a. The ends of insulating spacermembers 2%) and 29a are secured to the mounting chanriel 47 by bolts "'51.

in order re-reset the row of contacts 10 from their short-circuit closing position in "engagement with termin'als "13 and i la's shown in Fig. 2 totheir 'openposition as indicated in Fig. 4, a reset frame 55 is extended under the rowof contacts 10 andpivotally mounted on the terminal 14 by means of a bearingshaft 6. Thus frame 55 may be rotated counterclockwise to raise the entire row of contacts into full frictional latching relatio n'with the frictionelamping tension "elements 1 1. To raise thereset frarrie'55, a cam shaft 57 is 'rotatably mounted in the insulating spacers 2i) and a as shown in "Fig. 2 and provided with the cam 58 for raising the central reset pin 59 into engagement with the reset frame 55 and thereby apply 'suficient camming force to overthat are rotatably mounted on shaft having bearing blocks 66 secured to the U-shaped supporting members 45 and 46a by the bolts 67. The rounded ends 68 of the bell cranks 64 bear centrally against the slidably mounted plates 36 that carries the electromagnets 34 and 34a as indicated in Fig. 3.

Thus to reset the switch members l l and Na as well as the electromagnets'34 and 34a the cam shaft 57 is rotated by a suitable crank or other means to raise the reset pins '59 and thereby the frames 55 to move the switch members In against the bias of springs 1-2 and at the same'time move plate 36 to carry the electromagnets 34 and 34a into attractive engagement with the arinstures 33 and 33a against 'the bias of the compression springs 4t and 48a. Thus when the contacts it are raised to their fully open position as shown in Fig. '4, the 'electroma'gets '34 and 3421 will be brought into sufficiently close attractive relationship with the armatures 33 and 33a to magnetically attract the 'armatur'es and thereby apply a -force to the end of lever 28 sufficient to hold the rows of contacts it and 10a in their fully open position between the friction clamping elements 11 and lie. ence when'cam shaft 57 is rotated to return the pins 59 and "bell cranks '64 to their released position as shown in Fig. 3, the electromagnets 34 and 3421 will be held in "magnetically attractive relation with the ar-' matures 33 and 33a to apply the strong biasing force of the compression springs 40 to frictionally latch the rows of contacts '10 an'dliia in their fully open position.

In order "substantially instantaneously to release the armatures 33 and 330, each of the electro'magnets 34 and 34a is providedwith a special flux shifting 'p'ole face construction and a special flux shifting winding 76. This arrangementis such that uponenergization of the flux shifting winding 76 in response to a predetermined electrical condition, the flux that normally magnetically holds'armatu're in engagement with the'poles of electromagnet 34 is substantially instantaneously shifted from the armature 33 through the air gaps 7'1 thereby substantially instantaneously deene'rgizing and releasing the armature 33. Consequen'tly the spring biasing force that frictionally clamps the switch members "10 between the friction'elements 11 is substantiallyinstantaneously released. Hence the biasing springs 12 immediately operate the row of contacts 10into short circuitclosing "engagement between 'the'terminals 13 and 1%. Oscillograph tests haveshown that the time from releas'ing ihe armature 33 to the completion of the closing movement of the row of switch "members or contacts 10 was approximately 52 Omicroseconds and that the time required for shifting the flux from the armature 33 was approximately 2 00 microseconds. Thusthe total time of -response and operation was'less than fi of asec- 0nd. siich ultra h ig hspeedperform'ance results from the strong switch -'contact biasing forces employed, the 'infiziites'irnal 'unclamping motion of "the friction clamping elements required to release the row of contacts as wella's from the relatively small mass of the contacts and "coopcr ating parts of the switchmechanism and the relatively sr'nall distances rnovedthereby. Also the tests haveshown that with "the "im roved high speed switch construction, short circuit currents of at least 60,000 amperes can be successfully Carried.

-I'n con'tactshort cir'cuiting service for mechanical rectifiei's' the - thr e'e terminals 13,14 and 14a maybe connected dir'ectlyto thethree phase power lines sup'plying'the alternating'curr'ents to be rectified. Up'on'closure of'the-rows of contacts 10 and ltla'the alternating current supply'lines are imm'edia'tely short circu'ited to eliminate burning or other Ila'rn'age to the'rectifie'r cont'acts when 'thefiux ingwindings '70 of the elec'trornagnet's 34 "and 34a are connected to be energized in accordance with predetermined "are back electrical 'conditions. This effectively protects therectifier contacts and allows the ordinary'circuit breakers of adequate interrupting capacity to protect the alternating current lines.

In the modification shown in Fig. 6, the interleaved rows of switch members and friction clamping tension elements 11 as wellas the biasing springs 12, terminals 13 and 14 are all constructed and arranged in the same manner as previously described. Likewise, the lever 28a is mounted on the fulcrum 29 for applying the lateral clamping force to hold the switch members 10 frictionally clamped between the elements 11 in the open position. In this case the clamping force may be applied directly to lever 28a by means of a suitable tension spring 80.

In order to render the tension spring 80 ineffective and thereby release the lateral clamping force applied to the elements 11, a piezoelectric releasing element 81 is provided for engaging with the end of lever 28a so as to move this lever the infinitesimal distance required to release the friction elements 11. As shown the piezoelectric element 81 is in the form of a hollow cylindrical column having one end provided with a rounded bearing member 82 for engaging with the fiat face 83 provided at the end of the lever 28a. The other end of the piezoelectric ele ment 81 is fixedly mounted preferably with suitable adjustment for bringing the rounded bearing member 82 into minimum pressure engagement with the face 83 when the piezoelectric element 81 is subjected to a relatively high voltage sufficient to cause an appreciable decrease in the physical length of the element 81.

In order to subject the element 81 to such high voltage, a conducting layer or coating 85 is formed around the outer periphery of the element and an inner conducting layer or coating 86 is provided on the inner surface of the cylindrical element. Both of these layers terminate short of the enlarged insulating ends 87 and 88 with which the element 81 is provided. Such coatings may be formed of metal foil or metal paint and charged by means of the conductors 90 and 91 connected with a suitable source of high voltage.

Under charge conditions the cylindrical or tubular piezoelectric element 81 will quickly change its physical form so as to increase its diameter and decrease its length. Thus when the bearing number 82 is adjusted into minimum pressure engagement with the lever 28a, the biasing force of spring 80 is maintained effective to clamp the friction elements 11 and the interleaved switch members 10 together with a sufficiently strong clamping force to hold the switch members 10 in the open position against the closing bias of the biasing springs 12. In order to render the biasing spring 80 ineffective, all that is necessary is to quickly remove the charging voltage to which the inner and outer conducting coatings of the piezo element 81 are subjected. This may be accomplished by a suitable electroresponsive short circuiting switch 92 or preferably by means of an electron tube having a grid that can be used to instantaneously render the tube conducting in response to a predetermined electrical condition.

As soon as the high energizing voltage is thus removed ineffective and thus removes the clamping force from the elements 11 so as to substantially instantaneously release the switch member 10 for operation to the closed position in accordance with their bias. Hence the high speed electroresponsive piezo element 81 can serve substantially the same purpose as the high speed releasing electromagnets 34 and 34a when the short-circuiting of the high voltage conductors 90 and 91 is arranged to be accomplished by suitable means responsive to a predetermined electrical condition either in closing the short-circuiting switch 92 indicated or in rendering an electronic short circuiting tube conductive. To reset the switch, members 10 are returned to their latching position in the manner previously described and voltage reapplied to element 81.

changes its physical form so as to decrease its diameter and extend its length. This renders the biasing spring80- While the high speed electroresponsive friction latch switch mechanism of present invention is particularly advantageous in rectifier contact short circuiting service, it will be apparent to those skilled in the art that the switch mechanism may be applied in other switching service wherever ultra high speed response and operation are desirable.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electroresponsive switch mechanism having in combination, a friction clamping device having a clamping member and electroresponsive releasing means therefor, and a circuit controlling switch having a biased current carrying switch contact member directly frictionally clamped by the clamping member to be released for circuit controlling operation upon response of the electroresponsive releasing means to a predetermined electrical condition.

2. A switch having in combination, a pair of spaced apart current conducting terminals, a bridging switch member having one end seated in current conducting relation on one of the terminals, a clamping device having 7 a pair of friction elements for clamping the other end of the bridging switch member therebetween, spring means for biasing the other end of the switch member into circuit closing engagement with the other terminal upon release of the friction clamping elements, and means including an electroresponsive device for releasing the clamping elements upon response of the electroresponsive device to a predetermined electrical condition.

3. An electric circuit controlling device having in combination, a clamping device having a row of laterally movable friction elements in parallel spaced apart relation and a fixed friction element in spaced apart alignment at one end of the row, biasing means including a spring having a connection engaging with the friction element at the other end of the row and including a normally energized electroresponsive device for laterally biasing the friction elements into clamping relation, and a row of biased switch members interleaved with and frictionally clamped between the elements to be released for circuit controlling operation upon deenergization of the electroresponsive device in response to a predetermined electrical condition.

4. A switch having in combination a pair of spaced apart current conducting terminals, a row of bridging switch members each having one end seated in current conducting relation on one of the terminals and provided with separate spring biasing means for biasing the other end of the bridging switch member into circuit closing engagement with the other terminal, means including a movable reset'element engageable with the row of bridging switch members for moving the members to the circuit opening position, a clamping device having a row'of friction elements interleavedwith the bridging switch members for clamping the other ends'of the bridging switch members to hold the members in the circuit opening position and means including an electrorespon sive device for releasing the clamping elements for circuit closing. movement upon response of the electroresponsive deviceitoiapredetermined electrical condition.

5; A high speed.electroresponsive switch -havingin combination an electric circuit'controlling switch having a movable switch member, means biasing the member to move from one circuit controlling position to another circuit controlling position, a pair of friction elementsmounted for relative lateral movement on opposite sidesof the switch member in'the one circuit controlling position, and means including an electroresponsive device operable when energized to apply a lateral force to'said elements to clamp the switch 'member therebetween prevent circuit controlling movement "of the switch memher in accordance with its bias until deenergization of said: device 'in're'sponse to a predetermined electrical condition.

6. An electric circuit controlling device having in com antennae binati'onafriction clamping device .for supplying acl-arnping force, said device including electromagnetic means having a normally attracted armature for transmitting the clamping force and provided with a flux shifting winding for releasing the armature, and a biased switch member frictionally clamped by the device to be .reelased for 'circuit controlling operation upon energization of the flux shifting winding. I

7. An electric circuit controlling device having in cornbinat-ion, a clamping device ,having a .pair of relatively movable friction clamping elements, means including an electromagnet having :an armature attracted thereby for holding the elements in clamping relation, said electromagnet having an intcrpolar air gap provided with a winding for shifting the hurt from the armature to release the clamping elements, and a biased switch member frictionaily clamped between the elements to be substantially instantaneously released for circuit controlling operation upon energization of the flux shifting winding.

8. An electric circuit controlling device :having in combination, a clamping device having :a row of resilient friction clamping elements :biased into parallel spaced apart relation, an independent biasing 'spiing having connections including a movably mounted electromagne't and an armature attracted thereby :for holding the elements in clamping relation, said electromagnet having an interpolar air gap provided with a winding for shifting the holding zfiux from the armature to releasezthe clamping elements, and arow of biased switch members interleaved and frictionally clamped bet-ween the elements to be substantially instantaneously :released .for circuit controlling operation upon energization of the vflux shifting winding.

9. An electric circuit controlling device :having in con bin'ation, 'a :friction clamping device having a releasable clamping spring provided with :a piezoelectric releasing element, and a biased current carrying "switch :contact member directly fric'tionally clamped by the device to be released upon apredetermined variation :in :the energiza tion I of the piezoelectric element.

.10. An electric circuit controlling device having in combination, clamping means including a pair of relatively movable friction clamping elements, means including a spring for biasing the elements into dlamping relation, means including a piezoelectric element for releasing the elements, and "a biased switch member frictionally clamped between the elements to be released for circuit controlling operation upon deenergization of the piezoelectric element.

11. An electric circuit controlling :ldevice :having in combination, a clampingdevice having 'azrow of resilient friction clamping elements biased into parallel spaced apart relation, an independent biasing spring having con nections for holding the elements in clamping relation, means including apiezoelectric element for releasing :the clamping elements, and;a-'row=of biased switch members interleaved with and frictionally clamped between 'the elemnts .to be released :for circuit controlling operation upon -deenergization the piezoelectric element.

An electroresponsive zswitch mechanism :con rpns- .ing a pair of friction ctarrming members etieast sun: :of whichlis resilient, is'aid (clamping members i-having :a'djacent clamping surfaces disposed in parallel spaced "apart relation, means including an electroresponsive device .operable when energized to apply clamping pressure to said membersina direction normal -to :said clamping surfaces, amovable switch member normally held in clampingzrelation between said clamping :surfaces and biased for switch'actnating movement in a direction parallel :to said clamping surfaces, means responsive 10.53, predetermined ailil'y engagealile with .saidzswitch member to move said relationship,

switch member against its bias and reset said switch member in clamping position.

.13, An electroresponsive switch mechanism comprising a pair of friction clamping members at least one of which is resilient, said clamping members having adjacent cIamping surfaces disposed in parallel spaced apart relation, means including a spring applying clamping pressure to said members in a direction normal to said clamping surfaces, a movable switch member normally held in clamping relation between said clamping surfaces and biased for switch actuating movement in a direction parallel to said clamping surfaces, and electroresponsive means operable when ldeenergized to render said spring inetiective to apply said clamping pressure thereby to release said switch member for rapid switch actuating movement "under the influence of its bias.

1 An electroresponsive switch mechanism comprising a pair of friction clamping :members at least .one :of which :is res lient, said clamping members having adiacent clamping surfaces disposed in parallel spaced apart an electromagnet including a movable armature operable when energized to apply clamping pressure to'rsaid members in a direction normal to said clamping surfaces, a movable switch member normally held in clamping relationbetweensaid clamping surfaces and biased for switch actuating movement in a direction parallel to said clamping surfaces, and means responsive to a predetermined electrical condition for deenergizing said armature rtoirelease said pressure and thereby release said switch .rnember for rapid switch actuating movement under the influence .of its bias.

:15. An electric circuit controlling device having in combination, a stationary support having a row of resilient friction clamping elements mounted thereon in parallel spaced apart relation, means for applying a lateral clamping pressure upon said element, means including an ele'ctroresponsive device operable when deenergized 'to release said lateral clamping pressure, and a row of movable switch members interposed each between an adjacent pair of said elements in frictionally clamped relation, and means biasing said switch members for movement from between said elements upon release of said clamping pressure in response to deenergization of said e'lectroresponsive device.

16. An *electroresponsive switch mechanism comprising a pair of friction clamping members at least one of which is resilient, said clamping members having iadjacentclarnp'ing surfaces disposed in parallel spaced apart relation, an electromagnet including a resiliently mounted frame member "and a movable armature operable when energized to apply clamping pressure to said members in a direction normal to said clamping surfaces, a movable switch member normally held inra clamped position between said clamping surfaces andbiased Ifor switch actua'ting movement away from said clamped position in a direction parallel to said clamping surfaces, means Ie 'movahleresetting meansreleasabl-y engagealiie with said switch member to move said switch member against its bras into said clamping relation and s'imultaneouslylengageao'le with said frame member to .move said frame member into attractive relation with said armature.

References (Jitedh'r the 'file of this patent UNITED STATES PATENTS 1,427,369 'Fortescue Aug. 29, I922 32,112,912 Lindsey Sept. "12, 1939 2,365 ,738 Williams Dec. '26, 1944 12,509,271 'iieifery May 39,, 19

vnonzero PATENTS 1 126,057 Switzerland June 1, 19-28

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